Radiation beam pattern recorder



Sept 15, 1953 A. F. Bisel-IOFF RADIATION BEAM PATTERN RECORDER 2 Sheets-Sheet l F'iled April 26, 1951 SePt- 15, 1953 A. F. BISCHOFF 2,651,953

RADIATION BEAM PATTERN RECORDER Filed April 26, 1951 2 sheets-sheet 2 ngz.

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o o o o ./5-2 e l EN o' o o o g o W55 a o o o o l o g o o o 0 5 0 o o a o no o `55H o o o sin* 52m/o 55m 54M 55W 4H w53# 52m I5-1r" 0 o g o o o o Q o 0 o Of-`5f l a g o o o g c o o o g O O Q 0 O C l Q Q o o o o o 0 0 0 o C Q 0 I 0 I C 0 0 0 I 0 0 C 0 l o 0 n g n o o n O O C O g O 0 o 0 0 c I 0 o 0 o g o 0 o l o g o o o o o o o o o o o Inventor;

Alfed F Bischoff,

bg )Q J m Hisv Attorneg.

Patented Sept. 15, 1953 Alfred F. Bischoff, Ballston Spa,

'-N. "-Y., assignor to General AElectric Company,acorporation of New York VVApplication vApril 426, 1951, Serial No.,223,00.6

I3 Claims.

"This invention relates `tol recording devices and more lparticularly to recorders for vplotting the beam intensitypatterns of radiation devices.

Inflaboratory andproduction testing of light beam-radiation devices or light sources, such as 'forexample vsealed 'beam automobile headlights, itjis often necessary to measure the light'beam pattern lat a 'den'itedistance from the source. The method ordinarily followed in obtaining the desired lightpattern is to set up aphotoelectric cell "at the point where the pattern is desired. Then-the`light source is tilted vertically and rotatedh'orizontallythrough a number of steps so thatthe vphotoelectric cell is subjected to the intensities of Vvarious spotsthroughout the light beam pattern. 4The output of the photoelectric vcell and 'its'associated `amplifier is recordedmannelly-for each step. In order'to determine the location of ,the'variousstepsor spots beingmeasured in thelight pattern, a flashlight, which producesa narrow lightbeam, is fastened vto the lightunder test and` pointed in the opposite direction from thelight. The narrowbeam produced "by the flashlight falls upon. a calibrated xgrid board positioned `behind the flight source. Byobserving the location of thepoint of plight produced on `the grid'board, the corresponding location ofthe spot in the light pattern Ubeing measured by the photoelectric cell can be determined andrecorded. By repeating-thisproc ess point-by-point, a flux pattern can be .developed. "The development of an entire 'iiux or beam pattern is, however, obviouslya laborious, time-fconsumingprocess.

.Thuagreat utility eXistsJor alrecor'der which would automatically Y`plot Jthe 'beam A pattern of the headlight. However, thattisbut .one example of numerous applications which exist jfor an automatic 'beam pattern recorder. vAnother application "for which such a recorder could be adapted would be in `plotting the beampattern produced by ,an ultra-high frequency radiation 'device such as a radar antenna. yStill another use to which the automatic recorder could'be put wouldbeinplotting nuclear radiationppattems.

`VIt'is a general object of thisinvention,'there fore, to I`provide new .and improved means for plotting the.bearn, ,pattern of a radiation device, and in the fulfillment thereof, it'isa more specie-.object ofthisinvention toprovide. an automatic ,light beam 4pattern ,recorder v for ,plotting the flux-.pattern cfa light source.

vThe beampattern recorder of this invention employs a radiation detector device which pro- 2 duces electrical signalsin response to actuation ,b y a beamof radiated energy. The radiation detector device ,is positioned to intercept the beam of whose intensity pattern a plot isdesired, and the beamprcducing ,device is mounted on a supporting deviceso vthat it is rotatable or oscil- 'hativeabdut an axis and may also be tilted with vrespect to the axis. ",The supporting device is turned in synchronism with a drum upon .which is mounted a helical conductor or helix. Fed between the helix and an electricallyoonducting printingbar, .which together comprise a 'printing device, is an electro-sensitive recorder material. Pulses of electrical voltage indicative of the .level oibeam vintensity are Suppliedacross the :printingbar land the helix ,by a 4pulse forming circuit which "is actuated bythe electrical signalshproducedby the radiation detectordev1ce.

AI'Ihepulse forming circuit contains an amplitudelevelselection circuitcomprising a plurality of kparallel connected amplitude level selection channels, each of which produces a momentary signal ornpulse in responsekto a diiierentlevel of signal from the .radiation detector device. 4By correlating .the rotation of the vhelix with the movement of the beam producing device, each mark -left on 'theelectro-sensitive recorder ma- ,terial'ibythe vpulses will'be indicative of the presenceand position of a certain level of `intensity in the beam pattern. Proper rotation and ltiltingr ofthe beam producing device, Aso that :the radiation detector device scans representative lines throughout'the area of the'beamresults in the marks left onthe electro-sensitive recorder mayterial'by the pulses beingindicative of theintensitynpattern of ,the beam.

Alternatively a stylus-type single point printing device canlbe used to record the beamppattern. kIn such a device the stylusis moved back Vand` 'forth above a moving strip of recording material `jin accordance'with-the rotary or oscillatory motion of rthe beam-producing device, the direction of motion of vthe stylus being transverse to the direction of motion of the recording material. The rate of movement of Ythe recording materialis correlated with the rate at which. theibeamL-producing deviceis tilted. The output of thepulse viorming circuit is applied to the printing device'sogthat upon its receivinga pulse, the stylus either touches the` recording material tjoleave a vmarkI or else supplies a spark which leaves a mark on Athe recording material. By this meansaplot of the beam pattern is secured.

- Thus this inventionis not restricted to any particular type printing device since several different types may be used to record the beam pattern.

The different types of printing devices are similar, however, in that in each mark-making means is employed selectively to make marks on a moving strip of recorder material along a line transverse to the direction of movement of the strip. The marks are made in response to electrical pulses supplied to the device from the pulse forming circuit and the mark making means and the radiation device are interconnected to cause the position of the marks to be controlled by the simultaneous positions of the radiation device.

For a better and more complete understanding of this inventiony together with additional objects and advantages thereof, reference should now be had to the following description and accompanying drawing in which:

Fig. l is a schematic diagram, partially in block form, of a light beam pattern recorder embodying this invention; and

Fig. 2 is an example of the type plot produced by the beam pattern recorder of Fig. l for a typical light beam.

Referring to Fig. l, in the particular embodiment of this invention illustrated therein, a light source, such as the automobile headlight I, is mounted on a rotatable bracket 2 which is actuated to move in oscillatory motion by motor 3 through shaft 4, worm and wheel 5, and crank and arm linkage 6 in the manner well-known in the art. A worm and wheel 1 mounted on bracket 2 is likewise driven from shaft 4 but through spur gears 8 and flexible shaft 9. Worm and wheel 1 functions to tilt light I up or down in the vertical direction as bracket 2 oscillates back and forth in the horizontal plane.

Motor 3 also drives a recording cylinder or drum |I'l through worm and wheel II. Wound on drum I is a one-turn helical conductor or helix I2. A printing bar I3 is located adjacent to and parallel with the axis of drum I0, and fed between printing bar I3 and drum I0 is a sheet of electro-sensitive recorder material, such as paper I4. Printing bar I3 is connected electrically to one of the output terminals of a pulse amplifier I5 while helix I2 is connected to the other output terminal. It is by means of electrical pulses applied between printing bar I3 and helix |2 that the beam pattern of light I is recorded on paper I4.

The pulse producing circuit of which pulse amplifier I5 is a part is actuated by the light beam of light I impinging upon a light beam detection device, such as photoelectric cell I6, which produces an electrical signal in response to the illumination thereof. The signal from cell I6 is fed to an associated D. C. amplifier I1 through circuit opening and closing means such as microswitch I8. Microswitch I8 is actuated by a cam Ilia which rides on the shaft of drum I0 and is a switch of the type which is alternately opened and closed by the movement of a single actuating rod or button.

From amplifier I1, the amplified signal is fed directly to an amplitude level selection circuit, designated generally by numeral I9, comprising a plurality of parallel connected amplitude level selection channels, three of which, |9a, |9b and |90, are indicated in Fig. 1. The circuit diagram for channel A is shown in full and will be described hereinafter. Channels B and C are shown in block diagram and may be identical with channel A. Although only three channels are illustrated, many more such parallel connected channels, each adjusted to operate at a different amplitude level, will normally be employed. By means of a switch 22, the signal from amplifier l1 may be supplied to amplitude level selection circuit I9 through an additional stage 20 of D. C. amplification. Alternatively, the output of additional amplifier 20 may be connected to energize a separate amplitude level selection circuit (not shown) connected in parallel with circuit I9 and preferably identical therewith.

Amplitude level selection circuit I9 produces momentary signals or pulses in response to different levels of applied signal, as will be more fully described hereinafter. 'Ihe output pulses of amplitude level selection circuit I9 are fed through a pulse shaping circuit 2| to pulse amplifier I5. Pulse shaper 2| may comprise any of the well known circuits for producing a pulse of constant amplitude and duration in response to unidirectional trigger pulses,` and may be, for example, a cathode-coupled triggered multivibrator.

There are a number of circuits well known in the art which will produce a sudden signal or pulse at their output terminals in response to a certain level of voltage applied to their input terminals and which mayy therefore, comprise the voltage amplitude level section circuit employed in my invention. A preferred circuit, however, is shown as amplitude level selection channel A in Fig. l. 'Ihe amplified signal output of amplifier I1 is fed through a channel decoupling resistor 23 to a voltage coincidence circuit 24 comprising a pair of cathode follower stages 25 and 25 including triode vacuum tubes 21 and 28 with respective cathode resistors` 29 and 30. A pulse transformer 3| is connected between the cathodes of tubes 21 and 28, and tube 28 is biased by an adjustable connection 32 from its control electrode to a voltage dividing network comprising resistors 33, 34 and 35 connected between a source of high voltage 36 and a common ground connection 31. A rectifying diode 38 is preferably also connected between the control electrode of tube 21 and the connection of resistors 33 and 34 to limit the amount of positive signal voltage which may be applied to the control electrode of tube 21.

In the operation of coincidence circuit 24, with no signal the cathode of tube 28 is much more positive than that of tube 21 and a saturating current iiows through pulse transformer 3| in one direction. As the signal supplied to the control electrode of tube 21 increases, a point is reached where the voltage on the cathode of tube 21 equals and passes beyond the voltage on the cathode of tube 2B. At this point, the current through transformer 3| drops to zero and a voltage pulse is generated across its secondary winding. As the voltage on the cathode of tube 21 continues to rise, the transformer is saturated by a current flowing in a reverse direction than that of the no signal condition. Although the signal voltage may rise far beyond the normal operating limit of tube 21, diode 38 functions to short-circuit this excessive signal and to limit the current through tube 21 to a point just sufcient to maintain saturation in transformer 3|. A decrease in signal voltage from this excessive signal condition such that the cathode voltage of tube 21 decreases through the cathode voltage of tube 28 will, of course, produce an output pulse from transformer 3| of opposite polarity.

Another coincidence circuit, not shown in the 5 .dra-wings. --which may beexnplcyed in thefaboveedescribedrcoincidence circui Acircuit idescribedfandshownfzas S. Patent 23354;930fenttled .-fElectri'c Ccntrcl l'Cir-- cuit .'granted `fen -August .1.1, :1944, Ito .Jerry L.

4I .and'delivered through vcoupling capacitor 45..to the control electrode cf the remaining-.half oLduo-triode tube 4.3. `Both halves of :tu-be. areconnected-to commonanode and cathodepresisters. -Sincepulse inverting-stage--42f.functions toinver-tv only .pulses .of one polarity, the; pulses supp1ied'to.both halves of .-duo;triode tube-l3v=are cfithe sameverfective polarity regardless of Athe polaritypf theoutput `-of .transformer 3l. Consequently, composite :unidirectional pulses are l derived from the voltagedeveloped yacross the common .anode resistor 46 `and rare connected, as `indicated, `to- .energize the `,pulse .shaping circuit .2.I.

In operation' of the recorder, .motor 3 -fzdrives light ,I and drum Infashereinbefore mentioned. The,.degree,of-the oscillation of light I can'be varied .bychangingthe :sizefcf .crank "and arm mechanismt. The gearingzof-:aworm and-@wheel l5 :is...twice that'of worm.and .wheel l I..I .so .that drum I0 lmaires onecomplete revolutioniforfeach half-oscillationorfsweep.of the light. In other words., for .the left 'to rightsweep fof light `I., drum I.0 makes yone-complete revolution, while for.the'righttoleftwsweep @flight-I .it .makes-another complete revolution. The angularfsweep of .light :I mustbefat least as'wide-.asthe angle subtended by its beam. :For example, fassume that the beam@ pattern .oflight|. subtendsa horizontalangle of 1 approximately 15. Then ,for a eompleteplotto be made, thelight'mustsoscillate in `the horizontal plane .fat f least fl 1/2 on either. sidev of the.straight.,line between thezcenter .,position .of .light vI and photoelectric .cell l t6. '.[heposition of .drum weis .-.synchronized Avv-ith that oilight I sothatyv-hen light Itisateeither end of.its sweep, the. A.extremities Y of lhelix .4.2 `:are directly above printing. har I3.

"The-pulse formingcircuit is actuated-.typhotoelectric cell .I6 .for either .the .left or :right sweepsf light I or..for..the righttoleft: sweeps ofllightfl, but not for..both.since cam .Ia `alterternately .opens .and .closes ,microswitch `.I8 -for each revolution of (drum rvItifarid .thus for each half-oscillation of ,light .I..

Aslight I oscillatesback.andiorthin.a hori zontal. direction, itis vslowly tilted infthe .vertical direction .by worm .and .-wheel FI. .Thuseach .circuitactuating sweep of. light Icauses-photoelectric cell I.6 .to scan v.a different line ...across the beam pattern. .The .number offsweeps-.necessary to plotthe pattern depends upcnltheffdein'ition requiredand .the Ahejightpf the teatri., ;e. .the vertical .angle .-subtended #by the fbeam. If .it ris assumed `that .light .i :is lccntinually :tilted .up-

award v.by wormf-:and v.wheel 1, then :it would the initially mounted zon :bracket '.2 iso :that yun "Fits airst 'rhorizontalfsweep vonly .the .extreme upper ,por-tion Vof the beam pat-tern wouldlstrikecell .I6. .-If light I -is.however,'tilted'.dowmvard .by worm .and gear vwheel 'I, the :light would Imeun-tedsothat on its -rst horizontalrsweep the .extreme'lower portion of the ybeam would..strike .cell I6. Thefeedingfofpaper I4'between-.helix .I2...and. -printing bar .I3 must he correlatedwith .tlrie-.speed-ofA light I to insuref'a.freshvsurfacecf .thepaperlying between .helix I2uand .printing .ba-r I3 .for each horizontal .recording sweep -lof .light I. :Paper I'lI :may be fed by -anycof .the .means Well know-n in the art.

.Each .horizontal .sweep 4of light -I causes .-.the ramount .of light Aimpinging. onphotoelectric cell I6to...incr.ease fromfa minimum to a-maximum .and-then .backto a .minimum again. The .maxi-- .mumlightintensityfalling on cell .I6 .will vary appreciably `for .diferentfsweeps .as .light I .is .til-ted. .Assuming the response of photoelectriccell t6.and .the .associated amplier I.'I to be linear, the .voltage .impressed on amplitude .level :selec- .tion .circuit I9 willvary .directly from. minimum to-maximum. to. minimum inaccordance with. the lightffalling.on..cell I6. Eachv of amplitudeilevel selection .channels .of circuit I9 is calibrated, such as by adjustment.ofconnection 4:l2 .onresistord, to produce` amomentary .signal orpulse upon a .diiTerent level-oramplitude oi- Atheapr'ilie'd voltage.

' The number of .amplitude level. selection ,channels used is determined by the number -flight level indicating or contourllinesdesired inthe plot of the beam pattern. For aplot .containingve contour lines, as is.'illustratedfinlFigQ, ve amplitude.lcvelselection channels, each .responsive to ...a .dilerentf level .of applied voltage, .would hei needed. If aplot .showing the less intenseou'ter edges of .thefbeam pattern .,is.desired, switch .1.22 Visthrown toincludethe additional stage A2.0.o'i` signal amplification. Alternatively... an additional amplitude level selection circuit may be connected nlpara'lle'l WithcirCuitIS and energizedhy the output famplierjz. Amplitude'level selection circuits OT essentially thesame .designcan thus be used'for'the Whole possiblerange of .applied signals. '.'Thisffeature vmakes it possible to-record light. contours 'differing in light intensity by mere thamtwo. hundredto one .and .st-ill maintain .a high degree of measurement accuracy.

The output pulses from circuit I9 are -fed throughpulsefshaping circuit. .2I .toj pulse amplifier I 5,-.and.thetcutput; .pulses .f'offpulse amplier tisare applied'iibetweenfhelix It'Z and printing .bar i3 :to

' progducevisiblermarks onpaper IIA. Pulse shapthem :fand feeds `them l-a's "pulses of substantially constant xarmilitudeduration to the commun pulse amplier M li5. 'If desired, .the output of one or more ofthe channels of ,circuit I 9 may be supplied to'a separatepulse shaping circuitconnected in parallel with ,circuitZL .The amplitude .fand/or duration-.of thepulsesproduced .bythese separate pulse .shaping circuits may be. .sl-ightly'diferent tha-utilese produced yby circuit .ZI lwith'i'.hefresult that .the i-contourlines associated .with .the channels -supplyingnsu-ch .separate pulse :shaping :circuits are: printed with. a distinctivemark onpaper Ir-:'tefrnakethenrzreadily distinguishable. *Piyrefccntouriinesithectlrer contours in the iinal plot are more easily viden-- tied than would otherwise be possible.

In operation, the voltage output of cell I6 and its associated amplifier I'I rises from a minimum to a maximum and then decays again to a minimum as the light beam sweeps across cell IB. As the voltage rises, first the one of the channels of circuit I9 responsive to the least applied voltage produces a pulse, then the one responsive to the next to smallest applied voltage produces a pulse, and so forth until the voltage reaches its maximum value. The number of channels actuated, of course, depends upon the maximum value reached by the voltage and for any beam, the maximum value reached by the voltage in turn depends upon the portion of the beam being scanned. Thus for a sweep across the extreme outer portion of the beam, none of the channels of circuit I9 may be actuated, While for a sweep across the center portion of the beam, all the channels of the circuit I9 may be actuated. The same number of pulses produced during the rise of the applied voltage will ordinarily again be produced during the decay of the applied voltage. During the decay, however, circuit I9 will produce pulses in the opposite order from that which occurred during the rise. The channel last to produce a pulse during the rise in applied voltage will be the rst to produce during the decay in applied voltage, and the first to produce during the rise will be the last to produce during the decay. This is, of course, due to the fact that the voltage levels to which the channels of circuit I9 are responsive occur in the reverse order during the decay of the voltage.

Since the movement of helix i2 down printing bar I3 is synchronized with the sweep of light I, the position of any mark caused by any one of the channels of circuit I9 indicates the presence and position of its associated level of light intensity in the horizontal line of the beam pattern scanned during the particular sweep in which the mark was made. II" a number of horizontal sweeps are made, and the light beam `tilted to a different vertical angle for each, the marks caused by any one channel form a contour line which is indicative of the line along which its associated level of light lies in the beam pattern. These light level indicating or contour lines, when considered one within another, give a plot of the light intensity pattern of the light beam produced by light I.

Fig. 2 illustrates a typical plot containing five contour lines produced by a system having five amplitude level selection channels. The contour lines resulting from the responses of the iive channels are numbered 5I, 52, 53, 54 and 55, in order of increasing level of light intensity necessary to produce pulses from the channels. The plot is started with the light I tipped vertically to an extent such that only the extreme upper or lower portion of its beam will strike the cell I6 as the light sweeps horizontally. When the light is, for example, at the left-hand limit of its horizontal travel, the ends of helix I2 are at the edges of the paper and cam I8a actuates switch I8 and closes it. Switch I8 remains closed while the beam of light travels across the cell IG, the drum I0 rotates, and the helix travels across the paper. As the light beam moves horizontally across the cell I6, the output of the D. C. ampliiier rises until a maximum is reached at the center of the sweep. In Fig. 2 this maximum voltage has reached the level necessary to cause a pulse to be produced by that channel which has been preset to respond to the D.I C. voltage produced by the least light inf tensity that it is desired to plot. This pulse, when shaped and amplified produces a mark 5Ia on the paper, the first mark produced in the plot.

As previously mentioned, each channel will produce a pulse each time its response level is passed by the D. C. Voltage output of the cell and amplier, regardless of whether the applied voltage is rising or falling. However, during the rst horizontal sweep, which produced the first mark 5Ia, the D. C. level did not exceed the response level of the selection channel, but merely `reached the necessary level and then fell again. Thus, only one pulse and one mark were produced.

As the beam continues to move horizontally and the beam intensity decreases, the voltage output of the cell amplifier continues to decrease. When the beam reaches the limit of its travel in this direction, the drum has made one complete revolution, and the helix is in position to start across the paper again. At this time, the cam I8a again actuates switch I8, but now the movement opens the switch. Thus, as the beam of light swings back to the left side, from which it started,`and the drum II) rotates in synchronism therewith, no D. C. voltage is produced by the amplifier and, of course, no marks are produced on'the paper record. After the beam has swung back, the switch is again closed by the cam and the circuits are ready to produce marks when the proper levels of voltage are applied.

By the time the second sweep starts the vertical tilt of the light has been altered slightly by the Worm and wheel l, and the paper has been ad` vanced between the drum ID and printing bar I3. As the beam starts its second left-to-right sweep and the drum and helix moves in synchronism with it, the intensity of light falling on the cell and the D. C. output of the amplifier again rise. The cell is now intercepting the beam nearer the center of the beam than during the lirst sweep, and so the intensity of the beam is somewhat greater. Therefore, the voltage level Vnecessary to actuate the lowest level channel of circuit I9 is reached sooner than during the rst sweep, and a mark 5Ib is produced nearer the edge of the paper than mark 5 l-a. The intensity of the light and the output of the D. C. ampliiier continue to rise after the mark 5Ib is produced, but the voltage does not become great enough to actuate the next higher level selection channel before the center of the sweep (and maximum intensity) is reached. As the intensity falls off beyond the center of the beam, the D. C. voltage falls from a higher value to the level for which the selector channel is set and another mark 5 I b is produced. The beam continues its movement until the righthand extreme is reached, at which time the switch I8 opens and the beam returns to the left side.

As the horizontal traces pass closer to the center of the beam on successive sweeps, more of the amplitude selection channels are actuated and more marks produced during each sweep. On those traces near the center of the beam the intensity is suicient to cause all live ofthe channels to produce pulses. Marks labeled 5m, 5211., 531i, 5411., 5511, 55u', 5411.', 5311', 521i', and 5In, are produced in order as the helix moves from left to right across the paper. The rst five marks are produced as the light intensity increases and the D. C. output rises through the various levels to which the ve channels are responsive. The last five marks are produced as the intensity decreases and the D. C. output falls off and again passes through the various response levels. AIt is apparent that the channel which is preset to have the highest response level will be the last actuated by the rising voltage and the first actuated by the falling voltage. Therefore, its marks form the inner contour, which is surrounded by contours representing decreasing light intensities as they are located farther from the center.

Below the center of the beam, the intensity of the light falling on the cell during each horizontal sweep starts to decrease, and the plot is completed when a sweep is made which results in only one mark or no mark being made.

As mentioned previously, this invention is not restricted to plotting the pattern of light beams. It may be used for any type of radiation beams for which detecting means exist. It would be especially useful in ultra-high frequency work. For example, to plot the beam pattern of a radar antenna, the only change necessary in the illustrated circuit would be substitute an antenna and an ultra-high frequency detecting means, such as an electron discharge device, for example a diode detector, ior the photoelectric cell. Likewise, nuclear radiation patterns could be recorded if a suitable detector were substituted for photoelectric cell IS. Therefore, while the present invention has been described by reference to a particularembodiment thereof, it will be understood that numerous modifications may be made by those skilled in the art Without actually departing from the invention and it is aimed in the appended claims to cover all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a device for plotting the beam intensity pattern of a light source, a combination comprising a rotatable helical conductor; an electrically conducting printing bar positioned adjacent said helical conductor; means for feeding a sheet of electro-sensitive material intermediate said helical conductor and said printing bar; means for rotating said light source and means for tilting said light source with respect to the axis of rotation thereof; said helical conductor being connected to said light source rtating means for rotation together with said radiation device; a light beam detection device for producing an electrical signal in response to the illumination thereof positioned to intercept the light beam produced by said light source; a pulse forming circuit comprising an amplitude level selection circuit including a plurality of parallel connected amplitude level selection channels for producing electrical pulses in response to different levels of applied signal, each of said amplitude level selection channels being responsive to a different level of applied signal, said pulse forming circuit connected to be actuated by said radiation detector device; and. means including connections for applying the output of said pulse forming circuit between said helical conductor and said printing bar, whereby to produce marks on a sheet of electrosensitive material when said material is positioned intermediate said helical conductor and said printing bar, each of said marks being indicative of the presence and position of a certain level of intensity in said light beam.

2. In a device for plotting the beam intensity pattern of a light source, a combination comprising a rotatable helical conductor; an electrically conducting printing bar positioned adjacent said helical conductor; means for feeding a sheet of electro-sensitive material intermediate said helical conductor and said printing bar; means for rotating said light source and means for tilting said light source with respect to the axis of rotation thereof; means correlating the movement oi said helical conductor with the movement of said light source; a light beam detection device for producing an electrical signal in response to the illumination thereolF positioned to intercept the beam produced by said light source; means including connections for amplifying the output signal of said light beam detection device; a pulse forming circuit for producing electrical pulses in response to different levels of applied signals including in series relationship an amplitude level selection circuit, a pulse shaping circuit and an amplifying circuit, said amplitude level selection circuit having a plurality of amplitude level selection channels responsive to diierent levels of applied signals, said pulse forming circuit connected to be actuated by the amplified output signal from said light beam detecting device; and means including connections for applying the output of said pulse forming circuit between said helical conductor and said printing bar, whereby to produce marks on a sheet of electrosensitive material when said material is positioned intermediate said helical conductor and said printing bar, each of said marks being indicative of the presence and position of a certain level of intensity in said light beam.

3. A device for plotting the beam intensity pattern oi a radiation device comprising, a radiation detector for providing an electric signal in response to incident radiated energy, means for sweeping a beam of energy radiated from said device across said radiation detector, a recording device including a rotatable helical conductor and a printing bar adjacent said conductor parallel to the axis of rotation thereof, means for correlating the instantaneous rotational position of said helical conductor to the instantaneous angular position of said radiated beam relative to the position of said detector, a plurality of parallel-connected amplitude level selection channels connected to receive the electric signal from said radiation detector, each of said amplitude level selection channels providing an output electric pulse in response to a different amplitude level of the received electric signal, and means including connections for supplying the electric pulses produced by each amplitude level selection channel between said helical conductor and said printing bar, whereby to produce marks on an electrosensitive material when said material is interposed between said helical conductor and said printing bar, each of said marks being indicative of the presence and position of a certain level of intensity in said beam of radiated energy.

ALFRED F. BISCI-IOFF.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,500,746 Ellenberger Mar. 14, 1950 2,516,389 Hurvitz July 25, 1950 2,534,820 Hurvitz Dec. 19, 1950 FOREIGN PATENTS Number Country Date 595,313 Great Britain Dec. 2, 1947 

